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GEOG3068 Biogeography > L21: Genome diversity in plants > Flashcards

L21: Genome diversity in plants Flashcards

1
Q

What is karyology?

A

Study of cell nuclei by means of the number, size and shape of the chromosomes.

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2
Q

2n = 2x =18

2n =
2x =

A

2n = Somatic chromosome number (1 copy from each parental donors)

2x = Ploidy level (i.e. number of genome copies)

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3
Q

Chromosome diversity: which tissue?

Mitosis =

Meiosis =

A

Mitosis = Root tips

Meiosis = Flower buds, Sporangia

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4
Q

Chromosome diversity: which tissue?

Root tips =

Flower buds, Sporangia =

A

Mitosis = Root tips

Meiosis = Flower buds, Sporangia

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5
Q

What is the squash technique?

A

Pre-treatment: Cells arrested in metaphase (Ice-cold water, colchicine, 8-HQ, ABN).

Fixation: 3:1 absolute ethanol: glacial acetic acid

Hydrolysis: HCl 1N at RT or 60 0C

Staining: To enable visualising chromosomes (acetic orcein, feulgen (Schiffs’ reagent)

Squash: Spreading cells trying to get chromosomes in the same plane

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6
Q

Chromosome diversity: animals

A

Bulldog ant (Myrmecia pilosula) 2n = 2

Humans (Homo sapiens) 2n = 46

Lysandra butterfly (Lysandra atlantica) 2n = c. 440

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7
Q

Chromosome diversity: land plants

A

Daisy (Brachycome dichromosomatica) 2n = 4

Adders tongue fern (Ophioglossum reticulatum) 2n = c. 1440

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8
Q

Centromere position in the middle is what designation?

A

Metacentric (M)

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9
Q

Centromere position between middle and end is what designation?

A

Submetacentric (sm)

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10
Q

Centromere position close to end is what designation?

A

Subtelocentric (st)

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11
Q

Centromere position at end is what designation?

A

Telocentric (T)

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12
Q

Chromosome classification:

Holocentric chromosomes

A

Dispersed centromere sequence

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13
Q

Dysploidy

A

Stable change of the chromosome number due to structural rearrangements (e.g. centromeric fissions and/or fusions)

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14
Q

Aneuploidy

A

Change in chromosome number arising from addition/deletion of chromosomes during abnormal cell division

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15
Q

Genome size diversity: C-value

2C-value
1C-value

A

the amount of DNA in an unreplicated somatic diploid nucleus

the amount of DNA in an unreplicated haploid nucleus

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16
Q

Polyploidy

A

Presence of more than 2 sets of chromosomes

17
Q

Consequences of polyploidy:

A
  • Masking of recessive deleterious alleles
  • Promotes heterozygosis (increased fitness including growth rate, biomass and yield production)
  • Gene expression (including neo- functionalisation) leading to stress tolerance
  • Broader ecological tolerance and higher colonization ability than diploids

GEOG3068 Biogeography (23 decks)

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